A multilayer ceramic capacitor has hitherto been manufactured as follows. A large number of ceramic dielectric sheets onto which a metal powder paste is printed or sprayed are mutually stacked and laminated so as to obtain an electrode structure. After this laminate obtained by stacking and laminating is pressed and bonded into one piece, sintering is performed to connect external lead-out electrodes. This laminated ceramic capacitor has such characteristics that: the capacitance-volume ratio is high, the internal inductance is small, and it can be used in a high frequency band, for example, as high as GHz order, since it is possible to reduce the thickness of effective dielectrics.
Since ceramic dielectrics and internal electrodes are simultaneously sintered for this laminated ceramic capacitor, it is necessary that material for internal electrode has a higher melting point than the sintering temperature of the ceramics and does not react to ceramics. For this reason, noble metals such as Pt and Pd were used in the past as materials for internal electrodes. However, these materials had the disadvantage of high price. In order to eliminate this disadvantage, Ag—Pd alloys have been used as electrode materials by lowering the sintering temperature of dielectric ceramics of 900° C. or more and 1100° C. or less, or internal electrodes using inexpensive base metals have been put to practical use. Recent years have seen requirements for the use of laminated ceramic capacitors that can be operated in a high frequency band higher than the GHz order. For this reason, low electrical resistivity is a prerequisite condition for materials for internal electrodes and at present Cu is regarded as a promising candidate.
However, because of its low melting point Cu has the problem that the cracking and delamination of internal electrodes or poor sintering of dielectrics and the like are apt to occur due to a great temperature difference between melting temperature of Cu and sintering temperature dielectrics. Furthermore, Cu is easily oxidized in the sintering process by the oxygen in the atmosphere, posing the problem that the poor sintering of internal electrodes occurs and the electrical resistivity increases due to the mixing of oxides. Oxidation can be prevented by converting the atmosphere into a reducing one, however, ceramic dielectrics are then reduced and impossible to exhibit their good performance as dielectrics.
Therefore, a metal powder that starts sintering at a higher temperature than Cu and is not oxidized by the atmosphere during sintering is required.